Tough crystal nut cracked: Correct prediction of all three known crystal structures of a sulfonimide

Tough crystal nut cracked: Correct prediction of all three known crystal structures of a sulfonimide
March 10, 2011

(PhysOrg.com) -- It's not just the type of molecules a material is made of, the way in which they are arranged in space is important too. For many organic molecules, multiple crystal structures are known, and their physical properties can differ significantly. For example, a drug can be effective in one crystalline form but much less effective in another because it doesn't dissolve fast enough. Unfortunately, it has not been possible until recently to reliably predict crystal structures by using computer simulations. Frank Leusen and his co-workers at the University of Bradford (UK) are making significant progress on this front. As the scientists report in the journal Angewandte Chemie, they successfully used a quantum mechanical approach to predict the three known crystal structures of a sulfonamide.

Small differences in the production conditions, such as variations in pressure or temperature, can be enough to cause fine chemicals, such as pharmaceuticals, pigments, explosives, or agrochemicals, to crystallize in a different form. This can lead to problems with the production process or to undesirable product properties. It is correspondingly important to know which crystal structures are possible.

Scientists use computational chemistry methods to obtain information about molecular structures and crystallization processes. However, taking all of the parameters into account would exceed current computational capacities. “Precise, reliable predictions of the crystal structures of organic molecules have remained somewhat of a Holy Grail for crystallography,” says Leusen.

An international project regularly organizes blind studies in which research groups are asked to predict crystal structures. In 2007, Leusen and two co-workers were able to successfully predict the crystal structures of all four test compounds by using a quantum mechanical approach. A team led by Leusen then took on another test compound, a sulfonamide, which was the subject of a blind study in 2001; none of the participating teams was able to predict the crystal structure at the time. Interestingly, two additional, previously unknown crystal structures of this sulfonamide were discovered after the study. “By using the computational process developed by Marcus Neumann at Avant-garde Materials Simulation in Freiburg, Germany, we were able to correctly predict all three crystal structures,” says Leusen.

“Even though it is currently not possible to predict the outcome of a specific crystallization experiment under specific boundary conditions,” explains Leusen, “our results demonstrate that precise calculations of the lattice energy are sufficient to model crystallization thermodynamics and thus predict the different crystal structures of small organic molecules.”

More information: Frank J. J. Leusen, Molecule VI, a Benchmark Crystal-Structure-Prediction Sulfonimide: Are Its Polymorphs Predictable? Angewandte Chemie International Edition, http://dx.doi.org/10.1002/anie.201007488

Provided by Wiley (news : web)

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Smartphone sales to top 100 mn in Asia-Pacific: analyst

Smartphone sales to top 100 mn in Asia-Pacific: analyst
March 10, 2011

Smartphone sales are projected to hit 137 million units in 2011

Sales of smartphones such as Apple's iPhone4 are set to top 100 million units for the first time this year in the Asia Pacific market -- excluding Japan, an industry analyst said.

Sales of smartphones such as Apple's iPhone4 are set to top 100 million units for the first time this year in the Asia Pacific market -- excluding Japan, an industry analyst said Thursday.

Smartphone sales are projected to hit 137 million units in 2011, up from nearly 84 million last year, the technology industry research company IDC said in a statement.

"Smartphones were a hot item in 2010, with more than double the shipments of 2009," said IDC analyst Melissa Chau, adding that the growth came from the region's more developed markets such as South Korea.

"In 2011, IDC expects this fire to keep burning as mobile phone vendors race to get consumers on higher-margin devices, operators look to pull up revenues on mobile data, and mobile platform stakeholders battle to woo app developers," Chau said.

'Apps' refers to 'applications' that allow smartphone users to do a range of activities through their mobile phones including sharing pictures, playing games or checking their bank accounts.

In addition to operating as a telephone, smartphones allow users to send and receive emails, access Facebook and Twitter accounts, download movies, music and books and perform multiple other functions while on the go.

By 2015, three in five phones sold in the region will be smartphones, up from one in five in 2010, IDC said.

In the face of the smartphones onslaught, feature phones -- or devices that perform the basic functions -- still held their ground.

Sales of feature phones grew 17 percent in 2010, driven by low-end brands priced below $100 from China, India and other countries, IDC said.

(c) 2011 AFP

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IT Show 2011

IT Show 2011 at Suntec City starts today till Sunday.


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